Available controlled ovarian hyperstimulation protocols used in the network diagrams
| COH protocol | Abbreviation | Description |
| Long GnRH agonist | Long | Down-regulation with GnRH agonist 0.1 mg/day is performed from day 21 of the previous cycle. It is reduced to 0.05 mg/day from the start of the following cycle and continued until hCG administration. Gn is started at day 2–3 of menses using a dose of 300 IU of rFSH. The Gn dose is adjusted from day 6 of stimulation according to the ovarian response monitored until the day of hCG administration. |
| Short GnRH agonist | Short | GnRH-a administration is commenced at the same time as starting stimulation and continued until the day of hCG administration. Women receive GnRH agonist 0.05 mg/day starting on day 1 until the hCG injection and 450 IU rFSH daily starting on day 2. |
| Stop GnRH agonist | Stop | Administration of GnRH agonist 0.1 mg/day starts in the mid-luteal phase in the previous cycle and stops at the time of menstruation before starting Gn stimulation on day 2 of the menstrual cycle. Gn at 300–450 IU/day is initiated, and careful monitoring of follicular growth is performed using transvaginal ultrasound until >1 follicle on both ovaries reaches a diameter of 14 mm, when GnRH antagonist is injected subcutaneously until the date of hCG trigger. |
| Flare up GnRH agonist | Flare | Administration of GnRH-a 0.05 mg/day starts from day 2 of the cycle. GnRH agonist is administered subcutaneously and continued daily up to and including the day of hCG administration. |
| GnRH antagonist | GnRH-A | Gn is administered daily from menstrual cycle day 3; follicle monitoring is performed 5 days later. When the dominant follicles reach a diameter of approximately 14 mm, GnRH antagonist 0.125–0.25 mg/day is administered up to the trigger day. The dose of Gn can be adjusted according to ovarian response. |
| Delayed start GnRH antagonist | Delay | Administration of GnRH antagonist starts on day 2 or 3 of the menstrual cycle and continues until the ninth day. Then, ovarian stimulation with Gn is started from day 9 of the menstrual cycle until the day of hCG administration. |
| Mild ovarian stimulation | Mild | (i) Lower dose and shorter duration of Gn administration; (ii) using GnRH- antagonist to desensitise the pituitary gland and (iii) administering clomiphene citrate or tamoxifen or aromatase inhibitors with or without Gn and GnRH-antagonists. |
| Natural cycle | Natural | Starting on day 8, 1 or 12 of their cycle, regular ultrasonic evaluation of the endometrium thickness and mean diameter of the dominant follicle is performed. When the endometrium thickness is >8 mm and the diameter of the dominant follicle is 16–20 mm, ovulation is induced using hCG injection. |
| Luteal phase ovarian stimulation | LPOS | Between 0 and 24 hours after spontaneous ovulation or oocyte retrieval, patients with at least one follicle measuring <8 mm are administered hMG injection until the day of hCG administration. |
| Progestin-primed ovarian stimulation | PPOS | Administration of hMG and MPA starts daily from cycle day 3. Follicles are monitored 5 days later, and the dose of hMG is adjusted according to ovarian response. MPA dose is consistent up to the trigger day. |
COH, controlled ovarian hyperstimulation; FSH, follicle-stimulating hormone; Gn, gonadotropin; GnRH, gonadotropin-releasing hormone; hCG, human chorionic gonadotropin; hMG, human menopausal gonadotropin; LPOS, Luteal phase ovarian stimulation; MPA, medroxyprogesterone acetate; PPOS, Progestin-primed ovarian stimulation; rFSH, recombinant follicle-stimulating hormone.